For ophthalmic laser procedures involving the photodisruption of eye tissue, it is extremely important for the laser beam to be properly focused to a spot at a prescribed location inside the tissue. To make accurate incisions with the laser, it is extremely important that the focal spot have good definition. Specifically, it is desirable that the laser beam reach the focal spot free from aberrations that can distort the definition of the focal spot.
For ophthalmic laser procedures involving the cornea, the beam of laser light is generally passed through the anterior surface of the cornea and focused with the cornea. Unfortunately, since the anterior surface of the cornea in its natural state is nearly spherical, once a beam of light passes through the anterior surface of the cornea, aberrations are introduced into the beam that cause the beam to distort. For light beams that are focused to a focal spot within the cornea, these corneal induced aberrations distort the definition of the focal spot. It follows that more accurate incisions can be performed by reducing or eliminating these corneal induced aberrations.
For light beams that are focused to a focal spot within the cornea, both spherical aberration and coma cause a loss of definition of the focal spot. Conversely, it is known that when a light beam passes through a flat interface between two mediums, no spherical aberration or coma is introduced into the beam. Similarly, when a light beam passes through a nearly flat or slightly curved interface between two mediums, the effects of spherical aberration and coma are much less pronounced than for a light beam passing through a nearly spherical interface, such as the anterior surface of the cornea. As recognized by the present invention, the effects of spherical aberration and coma on light beams passing through the anterior surface of the cornea can be reduced or eliminated by reconfiguring the anterior surface of the cornea from its nearly spherical natural shape to a flatter configuration.
Generally, no two corneas are identical. Rather, the exact shape and curvature of the anterior shape of each cornea is slightly different. Consequently, each cornea in its natural state introduces different amounts of aberration into a light beam passing through the anterior surface of the cornea. For a light beam focused to a focal spot within the cornea, the unique shape of each cornea affects the definition of the focal spot differently. The present invention recognizes that the effects of spherical aberration and coma on light beams passing through the anterior surface of the cornea can be predicted by flattening the anterior surface of the cornea against a surface of known curvature. By using a surface of known curvature, a focal spot of known definition can be obtained and this knowledge can be used to ensure the desired surgical effect.
In light of the above, it is an object of the present invention to provide a disposable lens which will reconfigure the cornea for surgical laser procedures into a configuration wherein the effects of spherical aberration and coma on a light beam passing through the anterior surface of the cornea are reduced or eliminated. Yet another object of the present invention is to provide a disposable lens which will stabilize and maintain a proper orientation of the eye during ophthalmic laser surgery. Still another object of the present invention is to provide a disposable lens which will beneficially maintain near-normal intraoccular pressure during ophthalmic laser surgery. Another object of the present invention is to provide a disposable lens which is easy to use, relatively simple to manufacture and comparatively cost effective.